Way1 :

go to Window>Preferences>JavaScript>Editor>Mark Occurrences and unselect the checkboxes. That should do it.

Reason for this problem:

When u press ctrl for copy/paste, it assumes that is a "ctrl+mouseOver" operation, that we do before clicking on a method/variable name to reach its declaration point, or access its documentation. Hence, it tries to find all the occurrences of the text currently under the mouse cursor, along with its declaration point and documentation.

 

Way2:

Navigate to Window -> Preferences -> JavaScript -> Editor -> Typing -> When pasting

then uncheck Update imports.